I think George's story is indeed analogous to O-Sensei's chest push in the video clip. I think you missed in your analysis, though. O-Sensei maintains a connection to the ground at all times via simple, straightforward jin. As the incoming force begins to reach his hand, O-Sensei bounces down than then up so that the is an upward-angled, ground-based force meeting uke's incoming (more or less horizontal) force. Meeting such a force, uke is propelled up and back and his angle of attack actually means that his own force adds to the forces pushing him away. This is a common stratagem. It doesn't take any rotational movement to explain it. It just takes a little relaxed jin through O-Sensei.